Downeys Filling station Portlaoise

Project overview

Downeys Service Station, Portlaoise — completed March 2026, on time and on budget — involved the design, fabrication and installation of a larger‑than‑average petrol forecourt canopy. Our scope covered full structural engineering, shop‑drawing production, factory fabrication, site assembly and final erection. The finished canopy provides a high‑clearance, weather‑protected refuelling area with an architectural rooflight feature and integrated services while meeting strict safety and deflection criteria for a busy forecourt.

Design challenges

Three interrelated constraints made this project technically demanding:

Very long unsupported spans: clear spans between columns reached up to 18 m to maximise unobstructed refuelling lanes and customer flow.

Shallow overall depth: the client’s architectural brief and site constraints limited the canopy depth to 900 mm, restricting the section profile available to resist bending and shear.

Central rooflight: a large glazed rooflight in the centre required additional support that could not compromise the shallow depth or aesthetic continuity.

These factors produced conflicting structural requirements: heavy steel sections were needed to carry bending across 18 m spans, but the bulk of those members had to be accommodated within a 900 mm depth. The rooflight interrupted the main load path and introduced localised load concentrations and stiffness changes. Additionally, site safety and operational continuity demanded that structural assembly occur at ground level with a single lift into place, which required careful planning of temporary connections and stability during hoisting.

Innovative engineering solutions

To reconcile long spans with shallow depth we developed a hybrid internal‑splice strategy combining deep web plates, high‑strength flanges and precision notching. Key features included:

Hidden internal splice and notch system: rather than oversized external members, we configured multiple high‑capacity steel plates and hollow box sections nested within the 900 mm depth. Precision CNC notches and bolted splice plates allowed high moment capacity while keeping the external profile slim and architecturally clean.

Progressive splicing to control deflection: splices were detailed to permit controlled elastic rotation and redistribution during load uptake. This approach limited peak stresses at splice interfaces and ensured long‑span deflection remained within serviceability limits under live, snow and wind loads.

Reinforced rooflight support: a discrete secondary steel subframe was integrated beneath the rooflight. This subframe tied into the main spanning members through shear keys and bearing plates concealed within the 900 mm depth, transferring concentrated loads without visible bulk above the soffit.

Use of high‑strength steels and finite element modelling: we specified S355 grade flanges and web plates in critical zones and validated the configuration with detailed 3D finite element analyses, including staged erection and crane lift load cases.

Fabrication and quality control:

The complex internal splices and notches required precise fabrication tolerances. We produced full‑scale mockups of splice assemblies in the workshop to prove fit‑up and welding sequences. CNC plasma cutting and our qualified in house welding team were used for repetitive precision, and all critical welds underwent 100% visual inspection. Surface preparation and a durable industrial coating system were applied in the factory to reduce site painting and ensure long‑term corrosion protection for the forecourt environment.

Assembly and installation strategy

Safety and foresight drove the decision to assemble as much of the canopy as possible at ground level:

Preassembly modules: the canopy was broken into a small number of large modules sized for road transport and lift capacity. Each module included the internal splice assemblies, the secondary rooflight subframe, integrated duct routes for lighting and services, and temporary lifting collars.

Single crane lift: coordination with a heavy‑lift contractor secured a large mobile crane capable of a single, controlled placement of the preassembled canopy. Lift simulations and a rigging plan ensured centre‑of‑gravity control and minimal onsite bolting.

Temporary stability and final connections: temporary shoring pins and guide frames provided stability during the lift and alignment. Final structural bolting and welds were completed at height in protected conditions; all bolted joints used high‑strength friction grip bolts with calibrated tensioning.

Site logistics, safety and stakeholder coordination:

Portlaoise’s busy location required careful traffic management and on site house keeping, to ensure the construction site was able to progress with other trades and operations while we were assembling the canopy on site. Measures included:

A dedicated pedestrian and vehicle exclusion zone during lifts. All personnel followed a documented lift plan and permit‑to‑work system.

Close coordination with the client (Downeys Service Station), fuel dispenser installers and electrical contractors to sequence service integrations with minimal rework.

Testing, commissioning and handover

Following erection we undertook a staged commissioning programme: structural inspections, as‑built dimensional checks, load testing of rooflight support bearings, and verification of integrated service routes. Final checks included anti‑corrosion coating touch‑ups, lighting commissioning, and documentation for maintenance and warranty. The project was signed off in March 2026, meeting programme and budget targets.

Lessons learned and value delivered

Early integration of fabrication constraints into the structural design saved significant rework during shop detailing and improved on‑site erection speed.

Ground‑level assembly and a single lift reduced risk exposure at height, shortened on‑site activity duration and limited forecourt disruption.

Precision manufacturing (CNC and welding) plus full‑scale mockups de‑risked the splice system and ensured first‑time fit-up.

The completed canopy delivers the required unobstructed refuelling footprint, a refined architectural soffit with a central rooflight feature, and robust long‑term performance. By combining advanced structural detailing, modern fabrication methods and a well‑planned erection strategy, we successfully overcame the competing demands of long spans, a shallow profile and complex service integration — all within programme and budget for Downeys Service Station, Portlaoise.